Can permanent grassland soils with elevated organic carbon buffer negative effects of more persistent precipitation regimes on forage grass performance?

Agricultural practices enhancing soil organic carbon (SOC) show potential to buffer negative effects of climate change on forage grass performance. We tested this by subjecting five forage grass varieties differing in fodder quality and drought/flooding resistance to increased persistence in summer precipitation regimes (PR) across sandy and sandy-loam soils from either permanent (high SOC) or temporary grasslands (low SOC) in adjacent parcels. Over the course of two consecutive summers, monoculture mesocosms were subjected to rainy/dry weather alternation either every 3 days or every 30 days, whilst keeping total precipitation equal. Increased PR persistence induced species-specific drought damage and productivity declines. Soils from permanent grasslands with elevated SOC buffered plant quality, but buffering effects of SOC on drought damage, nutrient availability and yield differed between texture classes. In the more persistent PR, Festuca arundinacea FERMINA was the most productive species but had the lowest quality under both ample water supply and mild soil drought, whilst under the most intense soil droughts, Festulolium FESTILO maintained the highest yields. The hybrid Lolium × boucheanum kunth MELCOMBI had intermediate productivity and both Lolium perenne varieties showed the lowest yields under soil drought, but the highest forage quality (especially the tetraploid variety MELFORCE). Performance varied with plant maturity stage and across seasons/years and was driven by altered water and nutrient availability and related nitrogen nutrition among species during drought and upon rewetting. Moreover, whilst permanent grassland soils showed the most consistent positive effects on plant performance, their available water capacity also declined under increased PR persistence. We conclude that permanent grassland soils with historically elevated SOC likely buffer negative effects of increasing summer weather persistence on forage grass performance, but may also be more sensitive to degradation under climate change.

Biochemical composition changes can be linked to the tolerance of four grassland species under more persistent precipitation regimes

Climate models suggest that the persistence of summer precipitation regimes (PRs) is on the rise, characterized by both longer dry and longer wet durations. These PR changes may alter plant biochemical composition and thereby their economic and ecological characteristics. However, impacts of PR persistence have primarily been studied at the community level, largely ignoring the biochemistry of individual species. Here, we analyzed biochemical components of four grassland species with varying sensitivity to PR persistence (Holcus lanatus, Phleum pratense, Lychnis flos-cuculi, Plantago lanceolata) along a range of increasingly persistent PRs (longer consecutive dry and wet periods) in a mesocosm experiment. The more persistent PRs decreased nonstructural sugars, whereas they increased lignin in all species, possibly reducing plant quality. The most sensitive species Lychnis seemed less capable of altering its biochemical composition in response to altered PRs, which may partly explain its higher sensitivity. The more tolerant species may have a more robust and dynamic biochemical network, which buffers the effects of changes in individual biochemical components on biomass. We conclude that the biochemical composition changes are important determinants for plant performance under increasingly persistent precipitation regimes.

When things get MESI: The Manipulation Experiments Synthesis Initiative-A coordinated effort to synthesize terrestrial global change experiments

Responses of the terrestrial biosphere to rapidly changing environmental conditions are a major source of uncertainty in climate projections. In an effort to reduce this uncertainty, a wide range of global change experiments have been conducted that mimic future conditions in terrestrial ecosystems, manipulating CO₂ , temperature, and nutrient and water availability. Syntheses of results across experiments provide a more general sense of ecosystem responses to global change, and help to discern the influence of background conditions such as climate and vegetation type in determining global change responses. Several independent syntheses of published data have yielded distinct databases for specific objectives. Such parallel, uncoordinated initiatives carry the risk of producing redundant data collection efforts and have led to contrasting outcomes without clarifying the underlying reason for divergence. These problems could be avoided by creating a publicly available, updatable, curated database. Here, we report on a global effort to collect and curate 57,089 treatment responses across 3644 manipulation experiments at 1145 sites, simulating elevated CO₂ , warming, nutrient addition, and precipitation changes. In the resulting Manipulation Experiments Synthesis Initiative (MESI) database, effects of experimental global change drivers on carbon and nutrient cycles are included, as well as ancillary data such as background climate, vegetation type, treatment magnitude, duration, and, unique to our database, measured soil properties. Our analysis of the database indicates that most experiments are short term (one or few growing seasons), conducted in the USA, Europe, or China, and that the most abundantly reported variable is aboveground biomass. We provide the most comprehensive multifactor global change database to date, enabling the research community to tackle open research questions, vital to global policymaking. The MESI database, freely accessible at doi.org/10.5281/zenodo.7153253, opens new avenues for model evaluation and synthesis-based understanding of how global change affects terrestrial biomes. We welcome contributions to the database on GitHub.

Does previous exposure to extreme precipitation regimes result in acclimated grassland communities?

Climate change will likely increase weather persistence in the mid-latitudes, resulting in precipitation regimes (PR) with longer dry and wet periods compared to historic averages. This could affect terrestrial ecosystems substantially through the increased occurrence of repeated, prolonged drought and water logging conditions. Climate history is an important determinant of ecosystem responses to consecutive environmental extremes, through direct damage, community restructuring as well as morphological and physiological acclimation in species or individuals. However, it is unclear how community restructuring and individual metabolic acclimation effects interact to determine ecosystem responses to subsequent climate extremes. Here, we investigated, if and how, differences in exposure to extreme or historically normal PR induced long-lasting (i.e. legacy) effects at the level of community (e.g., species composition), plant (e.g., biomass), and molecular composition (e.g., sugars, lipids, stress markers). Experimental grassland communities were exposed to long (extreme) or short (historically normal) dry/wet cycles in year 1 (Y1), followed by exposure to an identical PR or the opposite PR in year 2 (Y2). Results indicate that exposure to extreme PR in Y1, reduced diversity but induced apparent acclimation effects in all climate scenarios, stimulating biomass (higher productivity and structural sugar content) in Y2. In contrast, plants pre-exposed to normal PR, showed more activated stress responses (higher proline and antioxidants) under extreme PR in Y2. Overall, Y1 acclimation effects were strongest in the dominant grasses, indicating comparatively high phenotypical plasticity. However, Y2 drought intensity also correlated with grass productivity and structural sugar findings, suggesting that responses to short-term soil water deficits contributed to the observed patterns. Interactions between different legacy effects are discussed. We conclude that more extreme PR will likely alter diversity in the short-to midterm and select for acclimated grassland communities with increased productivity and attenuated molecular stress responses under future climate regimes.

New bat species and records for the Adriatic Islands Vis and Biševo (Croatia)

The bat fauna of the Adriatic islands is relatively poorly known. Seven species were documented so far on the remote Adriatic islands of Vis and Biševo (Croatia). This study aims to increase knowledge on the bat communities on these islands. Bat echolocations were recorded between 30 April and 11 May 2018 at seven sites showing bat presence. Calls were identified to genus and species level where possible, which confirmed the presence of eight bat taxa on the islands. Three taxa were observed for the first time: Tadarida teniotis, Myotis sp. and Nyctalus sp. Results of this study increase the number of documented bat taxa on Vis from seven to ten and on Biševo from one to six. This study highlights the importance and benefits of utilizing passive acoustic devices at remote locations. Our findings suggest that bat communities and diversity might also be understudied on other islands in the Mediterranean, which could have important implications for bat conservation.

Risk of short-term biodiversity loss under more persistent precipitation regimes

Recent findings indicate that atmospheric warming increases the persistence of weather patterns in the mid-latitudes, resulting in sequences of longer dry and wet periods compared to historic averages. The alternation of progressively longer dry and wet extremes could increasingly select for species with a broad environmental tolerance. As a consequence, biodiversity may decline. Here we explore the relationship between the persistence of summer precipitation regimes and plant diversity by subjecting experimental grassland mesocosms to a gradient of dry-wet alternation frequencies whilst keeping the total precipitation constant. The gradient varied the duration of consecutive wet and dry periods, from 1 up to 60 days with or without precipitation, over a total of 120 days. An alternation of longer dry and wet spells led to a severe loss of species richness (up to -75% relative to the current rainfall pattern in W-Europe) and functional diversity (enhanced dominance of grasses relative to nitrogen (N)-fixers and non-N-fixing forbs). Loss of N-fixers and non-N-fixing forbs in severe treatments was linked to lower baseline competitive success and higher physiological sensitivity to changes in soil moisture compared to grasses. The extent of diversity losses also strongly depended on the timing of the dry and wet periods. Regimes in which long droughts (≥20 days) coincided with above-average temperatures showed significantly more physiological plant stress over the experimental period, greater plant mortality, and impoverished communities by the end of the season. Across all regimes, the duration of the longest period below permanent wilting point was an accurate predictor of mortality across the communities, indicating that increasingly persistent precipitation regimes may reduce opportunities for drought stress alleviation. We conclude that without recruitment, which was precluded in this experiment, summer precipitation regimes with longer dry and wet spells will likely diminish plant diversity, at least in the short term.

Decreased Immunoreactive Maspin Expression in Intermediate Thickness and Thick Primary Melanoma Lesions

Maspin is a member of the serpin family of protease inhibitors. It is a 42 kDa cytoplasmic protein that is reported to have tumour suppressor activity. The loss of maspin gene expression is correlated with increased invasiveness and the risk of metastases in breast cancer. We studied maspin expression in primary melanoma lesions obtained from 76 patients. Immunostaining of 5 μm sections for maspin expression was obtained using the citrate antigen retrieval method. The extent of immunostaining was scored by recording the proportion of immunoreactive cells and the intensity of immunostaining. Our results demonstrated that maspin expression was down-regulated in intermediate thickness and thick melanoma lesions compared with thin lesions. These results suggest that loss of maspin expression might play a role in melanoma progression, invasion and metastatic dissemination. Further studies are needed to clarify the clinicopathological significance of maspin expression in melanoma.

Evidence of an association between desmoglein 3 haplotypes and pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV, OMIM 169610) is a severe blistering disorder of the skin and mucous membranes, caused by the production of autoantibodies directed against the epithelial adhesive protein desmoglein 3. Although an association between PV and HLA class II alleles has been established, the genetic factors predisposing to the disease remain poorly understood, the rarity of PV hampering the recruitment of substantial patient cohorts.

OBJECTIVES

To investigate DSG3 as a candidate PV susceptibility gene.

METHODS

We examined five DSG3 single nucleotide polymorphisms (rs8085532, rs3911655, rs3848485, rs3794925 and rs1466379) in two case-control datasets respectively originating from the U.K. (62 PV patients, 154 controls) and northern India (28 patients, 98 controls).

RESULTS

In the U.K. sample, we observed a significant association between PV and the DSG3*TCCTC haplotype (Fisher's exact test P = 0.002). A related haplotype (DSG3*TCCCC) was associated with PV in the Indian dataset (P = 0.002). We also found that all British and Indian patients bearing DSG3 risk haplotypes carried at least one copy of a PV-associated HLA allele.

CONCLUSIONS

These results suggest that genetic variation of DSG3 may be an additive risk factor predisposing to PV and warrant further investigations of this gene.